1. Field of the Invention
The present invention relates to an image editing method and an image editing apparatus which performs an image processing such as combination of images and editing.
2. Description of the Related Art
An alpha mask is often used when clipping out an object (subjects such as a person, an object appearing in a picture) from an image, and executing a process for combining a clipped object with another image with a personal computer. An alpha mask is a binary image of the same size as an original image. For example, a region having an image value of 0 is a background, and a region having a pixel value of zero is an object. Only a background is replaced with another image by substituting only a pixel having a pixel value of 0 with a pixel of another image referring to an alpha mask when synthesizing the original image with another image. In such an image synthesis, it is necessary to set an alpha mask precisely. There is Photoshop of Adobe Systems Incorporated as software for performing the image combination. There will now be described an extraction tool adopted in the Photoshop version 6 (Adobe Photoshop 6.0 Japanese edition user guide, p. 154 to 157). Original images 1, 2, 3 and 4 shown in FIG. 4 as an example are combined to generate a composite image A shown in FIG. 5. In this case, a plurality of original images are arranged in a plurality of layers, respectively. The layer is for deciding the overwrite order of the original images. The composite image is generated by overwriting in turn the upper layers on the image of the lowest layer used as furring.
In other words, the original image from which an object is to be clipped and combined is selected. The pointer of a mouse is moved on this original image to set an object region. When a preview is carried out in a setting process, a background region is displayed by a given pattern (in this case whole area is in white) like the object image 3-1 of FIG. 6. Thus, the background region and the object region can be confirmed. The alpha mask in this case is shown in the alpha mask 3-1. When the border of this object region is deviated from the contour of an actual object as with the object images 3-2 and 3-3 of FIG. 6, it is possible to modify the image with a pen tool again. When the “Enter” button is pressed, an extraction dialogue becomes extinct in a result that the background region of the original image is erased. When the lower layer image is not disposed with respect to the original image beforehand, the background is displayed with being replaced with another pattern. However, if the lower layer image is disposed, a composite image is displayed.
In an example of the above-mentioned composite image A, the left side of the original image 3 appears on the composite image, but the lower side is covered by a car in front. Therefore, the object image 3-3 must be modified with respect to its object region. However, the object image 3-2 requires no modification of the object region, because the error in the object image 3-2 does not appear on the composite image. However, in the case of the extraction tool of Photoshop (Trademark), the composite image cannot be confirmed till the extraction work is finished. For this reason, even if it is the object image 3-2, the modification work cannot be omitted. As a result, a user must carry out a useless activity. As thus described, the conventional method must set a correct object region than need, resulting in increasing a working time.